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- 2. 12/11/2024 2 The causativeagent The single-celled obligate intracellular parasite Toxoplasma gondii CDC
- 3. 12/11/2024 3 The diseaseoccurs worldwide. Incubation period is 5–23 days. The Toxoplasma parasite can persist for long periods of time in the bodies of humans (and other warm-blooded animals), possibly even for a lifetime. In some areas more than 60% of populations older than 6 years may be infected with Toxoplasma. Infection is often highest in areas of the world that have hot, humid climates and lower altitudes, why? Epidemiology CDC
- 4. 12/11/2024 4 Signs andsymptoms The majority of people infected with T. gondii are asymptomatic. Flu-like illness, which may last for several months with fever and lymphadenopathy Severe toxoplasmosis may cause brain and eye damage Most infants who contracted intrauterine infection have no symptoms at birth, but they may develop symptoms later in life, (rarely symptoms may appear at birth). CDC
- 5. 12/11/2024 5 Toxoplasmosis Healthy peoplewho become infected with Toxoplasma gondii often do not have symptoms and the parasite remains inactive, but can be reactivated if the immunity declined. Congenital ocular infection → not detected at birth → 20-80% are discovered at adulthood. Ocular infection → chorioretinitis → retinal scar → blindness In immunocompromised persons → reactivation → fever, headache, confusion, seizures, poor coordination, pneumonia, encephalitis and death CDC
- 6. 12/11/2024 6 Toxoplasmosis inpregnancy If women infected before pregnancy → baby protected If women becomes newly infected during or just before pregnancy(3 months) → can transmit it to her baby. The earlier the infection in the pregnancy, the more severe the disease; including miscarriage, still birth and congenital toxoplasmosis ( Jaundice, microcephalus, macrocephalus and death). Often, infants have no symptoms at birth, but later in life may develop vision loss, mental disability, and seizures. CDC
- 7. 12/11/2024 7 CDC Classic triadof congenital toxoplasmosis Chorioretinitis Hydrocephalu s Intracranial calcification
- 8. 12/11/2024 8 The lifecycle of T. gondii CDC
- 9. 12/11/2024 9 The Lifecycle of T. gondii • The only known definitive hosts for Toxoplasma gondii are members of family Felidae like cats • The oocyst usually only shed 1-3 weeks → sporulation 1-5 days to become infective → ingested by intermediate hosts(rodents and birds) → tissue cyst → cats become infected after eating the intermediate hosts. • In the human host, the parasites form tissue cysts, most commonly in skeletal muscle, myocardium, brain, and eyes; these cysts may remain throughout the life of the host. CDC
- 10. Mode of transmission (Toxoplasmacannot be absorbed through intact skin). 12/11/2024 10 CDC 1. Eating Eating undercooked, contaminated meat (especially pork, lamb, and venison) or shellfish. Most common one Accidental ingestion of undercooked, contaminated meat or shellfish after handling them and not washing hands thoroughly Eating food that was contaminated by knives, utensils, cutting boards and other foods that have had contact with raw, contaminated meat or shellfish.
- 11. 12/11/2024 11 Mode ofTransmission CDC 2. Drinking water and unpasteurized goat’s milk contaminated with Toxoplasma gondii. 3. Accidentally swallowing the parasite through contact with cat feces 4. Mother-to-child (congenital) transmission. 5. Rarely, receiving an infected organ transplant or transfusion of infected blood
- 12. 12/11/2024 12 Diagnosis • Itis usually made by serological test. IgG measurement → to detect infection IgM + avidity test → to detect recent infection (pregnancy) • Direct observation of the parasite in stained tissue sections, cerebrospinal fluid (infrequently used). • Parasites can also be isolated from blood or CSF. • Molecular techniques that can detect the parasite’s DNA in the amniotic fluid for mother-child transmission. • Ocular disease is diagnosed based on eye examination + serologic testing. CDC
- 13. 12/11/2024 13 Treatment It isindicated in: Recently infected pregnant women Severe disease Immunodefic ient persons Recent active eye lesion CDC
- 14. 12/11/2024 14 Control andprevention Treatment: The drugs of choice → pyrimethamine and sulfadiazine (clindamycin or azithromycin), plus folinic acid. 1. Healthy persons → no need for treatment 2. Pregnant women → < 18 weeks → Spiramycin > 18 weeks → the above treatment 3. Ocular toxoplasmosis → if acute active lesion, then treat → if chronic with complete scar → no need 4. Immunocompromised persons → need treatment until their immunity is improved For AIDS patients treatment may continue for life. CDC
- 15. 12/11/2024 15 Control andPrevention • Cook food to an internal temperature high enough to kill harmful pathogens like Toxoplasma 70 C° . • The only way to tell if food is safely cooked is to use a food thermometer. • Freeze meat for several days at -18 C° temperatures before cooking to greatly reduce chance of infection. • Rinse fresh fruits and vegetables under running water. • Wash your utensils, cutting boards, and countertops with hot, soapy water after preparing each food item. • Do not eat raw or undercooked oysters, mussels, or clams (these may be contaminated with Toxoplasma that has washed into seawater). CDC
- 16. 12/11/2024 16 Control andPrevention • Do not drink unpasteurized goat’s milk. • Wear gloves when gardening and during any contact with soil or sand because it might be contaminated with cat feces that contain Toxoplasma. Wash hands with soap and water after gardening or contact with soil or sand. • Ensure that the cat litter box is changed daily. The Toxoplasma parasite does not become infectious until 1 to 5 days after it is shed in a cat’s feces. • Wash hands with soap and water after cleaning out a cat’s litter box. • Teach children the importance of washing hands to prevent infection. CDC
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